Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Senior debt:
Total debt	$ 430,000	$ 430,000
Less: Current maturities	(10,000)	(10,000)
Total long-term debt, net of current maturities	420,000	420,000
Revolving credit facility [Member]
Senior debt:
Total debt	240,000	235,000
Term loans [Member]
Senior debt:
Total debt	$ 190,000	$ 195,000